螺杆钻具挠性轴结构改进分析

Analysis of structural improvement of flexible shaft of screw drill

通过对现有某型号螺杆钻具挠性轴的结构尺寸分析,建立了挠性轴受力分析的有限元模型。有限元分析结果发现:原始挠性轴过渡区结构不合理,在过渡区存在应力集中现象。研究了挠性轴过渡区倒圆半径与应力集中系数的关系,得出了挠性轴上过渡区倒圆半径大于150mm时,可以消除应力集中现象的结论;同时研究了挠性轴直径、长度结构变化与提高挠性轴寿命的关系,提出了螺杆钻具挠性轴结构改进的3种可行方案,这3种方案均可消除挠性轴上的应力集中,为挠性轴寿命的提高提供了理论依据。

By analyzing the structural size of flexible shaft of the existing screw drill, the finite-element model of force analysis of the flexible shaft is established. The results from the finite-element analysis show that the transition region of original flexible shaft is unreasonable in structure since the stress concentration occurs in the transition region. The relationship between the inverted round radius and the stress concentration coefficient in the transition region is studied and it is concluded that the stress concentration can be eliminated when the inverted round radius is bigger than 150 mm. In addition, the relationship between the radius and length change of the flexible shaft and the increase of flexible shaft life is also studied, putting forward three kinds of viable schemes regarding the improvement of flexible shaft structure. The three schemes provide the theoretical basis for the improvement of flexible shaft life since they can eliminate the stress concentration in the flexible shaft.